1. Field of the Invention
This invention relates to a method and an apparatus for magnetically recording an analog signal and a digital signal. This invention also relates to a magnetic recording medium.
2. Description of the Related Art
Japanese published unexamined patent application 61-39784 discloses a method for magnetic recording and reproduction. According to the method in Japanese application 61-39784, a first magnetic head records an analog video signal on a magnetic tape while forming analog video tracks thereon. In addition, a second magnetic head records a digital signal on the analog video tracks. The first and second magnetic heads are different from each other in azimuth angle. A recording current for the digital signal is smaller than that for the analog video signal so that the digital signal will be written into a shallow portion of an analog video recording layer within the magnetic tape.
Japanese application 61-39784 teaches that the analog video signal and the digital signal can be in a common frequency band equal to or higher than a frequency of 1.5 to 2 MHz when the azimuth angles of the first and second magnetic heads are different from each other by 30xc2x0.
Japanese published unexamined patent application 6-14343 discloses a video recorder which records a VHS signal (an analog video signal) and a digital video signal on a magnetic tape. In the video recorder of Japanese application 6-14343, a first magnetic head writes the VHS signal into a major layered portion of the magnetic tape. In addition, a second magnetic head writes the digital video signal into a shallow layered portion or an upper layered portion of the magnetic tape. The first and second magnetic heads are different from each other in azimuth angle and gap width. The first magnetic head is composed of a pair of elements having azimuth angles of xc2x16xc2x0. The second magnetic head is composed of a pair of elements having azimuth angles of xc2x130xc2x0. The first magnetic head has a gap width of 0.4 xcexcm. The second magnetic head has a gap width of 0.2 xcexcm.
Japanese application 6-14343 indicates that the digital video signal is in a frequency band from about 2.3 MHz to about 12 MHz.
As the lower limit of a common frequency band for a VHS signal and a digital video signal drops, the digital video signal tends to more interfere with down-converted color components of the VHS signal during the reproduction of the two signals from a magnetic tape. Such interference decreases the quality of pictures represented by the reproduced VHS signal.
It is a first object of this invention to provide an improved method of recording an analog information signal and a digital information signal on a magnetic recording medium.
It is a second object of this invention to provide an improved apparatus for recording an analog information signal and a digital information signal on a magnetic recording medium.
It is a third object of this invention to provide an improved magnetic recording medium.
A first aspect of this invention provides a method of magnetic recording which comprises the steps of alternately using first and second magnetic heads to record an analog video signal on a magnetic recording medium while sequentially forming first tracks on the magnetic recording medium, the magnetic recording medium being fed with respect to a rotary drum at a predetermined speed, the magnetic recording medium being wound on an outer circumferential surface of the rotary drum along a part of a helix in a predetermined angular range, the first and second magnetic heads being attached to the rotary drum, the first and second magnetic heads being diametrically opposed to each other, the first and second magnetic heads being in a first predetermined height position with respect to the rotary drum, the first and second magnetic heads having different azimuth angles respectively; and alternately using third and fourth magnetic heads to record a digital video signal on the magnetic recording medium while sequentially forming and writing second tracks over at least portions of the first tracks on the magnetic recording medium, the third and fourth magnetic heads being attached to the rotary drum, the third and fourth magnetic heads being diametrically opposed to each other, the third and fourth magnetic heads being in a second predetermined height position with respect to the rotary drum, the second predetermined height position being different from the first predetermined height position, the third and fourth magnetic heads having different azimuth angles respectively, the azimuth angles of the third and fourth magnetic heads being different from the azimuth angles of the first and second magnetic heads, the digital video signal being in a frequency band wider than a frequency band of the analog video signal, the frequency band of the digital video signal including a frequency band of a frequency converted carrier chrominance signal of the analog video signal, the digital video signal being free from periodicity of its record waveform.
A second aspect of this invention is based on the first aspect thereof, and provides a method wherein a level of the analog video signal recorded by the first and second magnetic heads is greater than a predetermined level which is used in a case where only an analog video signal is recorded.
A third aspect of this invention is based on the first aspect thereof, and provides a method wherein each of the second tracks extends in an area containing a boundary between two neighboring tracks among the first tracks.
A fourth aspect of this invention is based on the first aspect thereof, and provides a method wherein the digital video signal results from subjecting an original video signal to a scramble interleaved NRZI process.
A fifth aspect of this invention provides a magnetic recording apparatus comprising a rotary drum; first and second magnetic heads attached to the rotary drum, the first and second magnetic heads being diametrically opposed to each other, the first and second magnetic heads being in a first predetermined height position with respect to the rotary drum, the first and second magnetic heads having different azimuth angles respectively; first means for generating an analog video signal; second mans for alternately using the first and second magnetic heads to record the analog video signal on a magnetic recording medium while sequentially forming first tracks on the magnetic recording medium, the magnetic recording medium being fed with respect to the rotary drum at a predetermined speed, the magnetic recording medium being wound on an outer circumferential surface of the rotary drum along a part of a helix in a predetermined angular range; third and fourth magnetic heads attached to the rotary drum, the third and fourth magnetic heads being diametrically opposed to each other, the third and fourth magnetic heads being in a second predetermined height position with respect to the rotary drum, the second predetermined height position being different from the first predetermined height position, the third and fourth magnetic heads having different azimuth angles respectively, the azimuth angles of the third and fourth magnetic heads being different from the azimuth angles of the first and second magnetic heads; third means for generating a digital video signal being free from periodicity of its waveform and being in a frequency band wider than a frequency band of the analog video signal, the frequency band of the digital video signal including a frequency band of a frequency converted carrier chrominance signal of the analog video signal; and fourth means for alternately using the third and fourth magnetic heads to record the digital video signal on the magnetic recording medium while sequentially forming and writing second tracks over the first tracks on the magnetic recording medium.
A sixth aspect of this invention is based on the fifth aspect thereof, and provides a magnetic recording apparatus wherein each of the second tracks extends in an area containing a boundary between two neighboring tracks among the first tracks.
A seventh aspect of this invention is based on the fifth aspect thereof, and provides a magnetic recording apparatus wherein the third means comprises means for subjecting an original video signal to a scramble interleaved NRZI process to generate the digital video signal from the original video signal.
An eighth aspect of this invention is based on the fifth aspect thereof, and provides a magnetic recording apparatus further comprising fifth means for controlling a level of the analog video signal recorded by the first and second magnetic heads to be greater than a predetermined level which is used in a case where only an analog video signal is recorded.
A ninth aspect of this invention is based on the fifth aspect thereof, and provides a magnetic recording apparatus wherein pictures represented by the digital video signal are equal in contents to pictures represented by the analog video signal.
A tenth aspect of this invention is based on the fifth aspect thereof, and provides a magnetic recording apparatus wherein the third means comprises means for compressively encoding a first video signal into a transport stream signal of a predetermined MPEG format; means for adding an error correction code signal to the transport stream signal to convert the transport stream signal into a second video signal; and means for removing periodicity from the second video signal in response to a pseudo random signal, and converting the second video signal into the digital video signal.
An eleventh aspect of this invention provides a tape-shaped magnetic recording medium having an array of first slant tracks and an array of second slant tracks, the first slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the second slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the azimuth angles of the second slant tracks being different from the azimuth angles of the first slant tracks, the second slant tracks extending over at least portions of the first slant tracks, the first slant tracks storing an analog video signal, the second slant tracks storing a digital video signal, the digital video signal being free from periodicity of its record waveform and being in a frequency band wider than a frequency band of the analog video signal, the frequency band of the digital video signal including a frequency band of a frequency converted carrier chrominance signal of the analog video signal.
A twelfth aspect of this invention is based on the eleventh aspect thereof, and provides a tape-shaped magnetic recording medium wherein the analog video signal stored in the first slant tracks is of a predetermined standard format, and a level of the analog video signal stored in the first slant tracks is greater than a normal level.
A thirteenth aspect of this invention is based on the eleventh aspect thereof, and provides a tape-shaped magnetic recording medium wherein each of the second slant tracks extends in an area containing a boundary between two neighboring tracks among the first slant tracks.
A fourteenth aspect of this invention provides a method of magnetic recording which comprising the steps of alternately using first and second magnetic heads to record an audio signal on a magnetic recording medium while sequentially forming first tracks on the magnetic recording medium, the magnetic recording medium being fed with respect to a rotary drum at a predetermined speed, the magnetic recording medium being wound on an outer circumferential surface of the rotary drum along a part of a helix in a predetermined angular range, the first and second magnetic heads being attached to the rotary drum, the first and second magnetic heads being diametrically opposed to each other, the first and second magnetic heads being in a first predetermined height position with respect to the rotary drum, the first and second magnetic heads having different azimuth angles respectively; alternately using third and fourth magnetic heads to record an analog video signal on the magnetic recording medium while sequentially forming and writing second tracks over the first tracks on the magnetic recording medium, the third and fourth magnetic heads being attached to the rotary drum, the third and fourth magnetic heads being diametrically opposed to each other, the third and fourth magnetic heads being in a second predetermined height position with respect to the rotary drum, the second predetermined height position being different from the first predetermined height position, the third and fourth magnetic heads having different azimuth angles respectively, the azimuth angles of the third and fourth magnetic heads being different from the azimuth angles of the first and second magnetic heads; and alternately using fifth and sixth magnetic heads to record a digital video signal on the magnetic recording medium while sequentially forming and writing third tracks over at least portions of the first and second tracks on the magnetic recording medium, the fifth and sixth magnetic heads being attached to the rotary drum, the fifth and sixth magnetic heads being diametrically opposed to each other, the fifth and sixth magnetic heads being in a third predetermined height position with respect to the rotary drum, the third predetermined height position being different from the first and second predetermined height positions, the fifth and sixth magnetic heads having different azimuth angles respectively, the azimuth angles of the fifth and sixth magnetic heads being different from the azimuth angles of the third and fourth magnetic heads, the digital video signal being in a frequency band wider than a frequency band of the analog video signal, the frequency band of the digital video signal including a frequency band of a frequency converted carrier chrominance signal of the analog video signal, the digital video signal being free from periodicity of its record waveform.
A fifteenth aspect of this invention is based on the fourteenth aspect thereof, and provides a method wherein the magnetic recording medium comprises a magnetic tape having a coercive force greater than that of a standard magnetic tape, and a level of the analog video signal recorded by the third and fourth magnetic heads is greater than a predetermined level which is used in a case where an analog video signal is recorded on the standard magnetic tape.
A sixteenth aspect of this invention is based on the fourteenth aspect thereof, and provides a method wherein each of the third tracks extends in an area containing a boundary between two neighboring tracks among the second tracks.
A seventeenth aspect of this invention is based on the fourteenth aspect thereof, and provides a method wherein longitudinal central lines of the third tracks are substantially coincident with longitudinal central lines of the first tracks, respectively.
An eighteenth aspect of this invention is based on the fourteenth aspect thereof, and provides a method wherein pictures represented by the digital video signal are equal in contents to pictures represented by the analog video signal.
A nineteenth aspect of this invention is based on the fourteenth aspect thereof, and provides a method wherein the azimuth angle of the fifth magnetic head is equal to the azimuth angle of the first magnetic head, and the azimuth angle of the sixth magnetic head is equal to the azimuth angle of the second magnetic head, and wherein the fifth magnetic head writes a third track over a first track formed by the second magnetic head, and the sixth magnetic head writes a third track over a first track formed by the first magnetic head.
A twentieth aspect of this invention provides a magnetic recording apparatus comprising a rotary drum; first and second magnetic heads attached to the rotary drum, the first and second magnetic heads being diametrically opposed to each other, the first and second magnetic heads being in a first predetermined height position with respect to the rotary drum, the first and second magnetic heads having different azimuth angles respectively; first means for generating an audio signal; second mans for alternately using the first and second magnetic heads to record the audio signal on a magnetic recording medium while sequentially forming first tracks on the magnetic recording medium, the magnetic recording medium being fed with respect to the rotary drum at a predetermined speed, the magnetic recording medium being wound on an outer circumferential surface of the rotary drum along a part of a helix in a predetermined angular range; third and fourth magnetic heads attached to the rotary drum, the third and fourth magnetic heads being diametrically opposed to each other, the third and fourth magnetic heads being in a second predetermined height position with respect to the rotary drum, the second predetermined height position being different from the first predetermined height position, the third and fourth magnetic heads having different azimuth angles respectively, the azimuth angles of the third and fourth magnetic heads being different from the azimuth angles of the first and second magnetic heads; third means for generating an analog video signal; fourth means for alternately using the third and fourth magnetic heads to record the analog video signal on the magnetic recording medium while sequentially forming and writing second tracks over the first tracks on the magnetic recording medium; fifth and sixth magnetic heads attached to the rotary drum, the fifth and sixth magnetic heads being diametrically opposed to each other, the fifth and sixth magnetic heads being in a third predetermined height position with respect to the rotary drum, the third predetermined height position being different from the first and second predetermined height positions, the fifth and sixth magnetic heads having different azimuth angles respectively, the azimuth angles of the fifth and sixth magnetic heads being different from the azimuth angles of the third and fourth magnetic heads; fifth means for generating a digital video signal being free from periodicity of its waveform and being in a frequency band wider than a frequency band of the analog video signal; and sixth means for alternately using the fifth and sixth magnetic heads to record the digital video signal on the magnetic recording medium while sequentially forming and writing third tracks over at least portions of the first and second tracks on the magnetic recording medium.
A twenty-first aspect of this invention is based on the twentieth aspect thereof, and provides a magnetic recording apparatus wherein the magnetic recording medium comprises a magnetic tape having a coercive force greater than that of a standard magnetic tape, and a level of the analog video signal recorded by the third and fourth magnetic heads is greater than a predetermined level which is used in a case where an analog video signal is recorded on the standard magnetic tape.
A twenty-second aspect of this invention is based on the twentieth aspect thereof, and provides a magnetic recording apparatus wherein each of the third tracks extends in an area containing a boundary between two neighboring tracks among the second tracks.
A twenty-third aspect of this invention is based on the twentieth aspect thereof, and provides a magnetic recording apparatus wherein longitudinal central lines of the third tracks are substantially coincident with longitudinal central lines of the first tracks, respectively.
A twenty-fourth aspect of this invention is based on the twentieth aspect thereof, and provides a magnetic recording apparatus wherein the fifth means comprises means for subjecting an original video signal to a scramble interleaved NRZI process to generate the digital video signal from the original video signal.
A twenty-fifth aspect of this invention is based on the twentieth aspect thereof, and provides a magnetic recording apparatus wherein pictures represented by the digital video signal are equal in contents to pictures represented by the analog video signal.
A twenty-sixth aspect of this invention is based on the twentieth aspect thereof, and provides a magnetic recording apparatus wherein the azimuth angle of the fifth magnetic head is equal to the azimuth angle of the first magnetic head, and the fifth magnetic head is smaller in track width than the third and fourth magnetic heads, and wherein the azimuth angle of the sixth magnetic head is equal to the azimuth angle of the second magnetic head, and the sixth magnetic head is smaller in track width than the third and fourth magnetic heads.
A twenty-seventh aspect of this invention is based on the twentieth aspect thereof, and provides a magnetic recording apparatus wherein the fifth means comprises means for compressively encoding a first video signal into a transport stream signal of a predetermined MPEG format; means for adding an error correction code signal to the transport stream signal to convert the transport stream signal into a second video signal; and means for removing periodicity from the second video signal in response to a pseudo random signal, and converting the second video signal into the digital video signal.
A twenty-eighth aspect of this invention provides a tape-shaped magnetic recording medium having an array of first slant tracks, an array of second slant tracks, and an array of third slant tracks, the first slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the second slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the third slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the azimuth angles of the second slant tracks being different from the azimuth angles of the first slant tracks, the azimuth angles of the third slant tracks being different from the azimuth angles of the second slant tracks, the second slant tracks extending over the first slant tracks, the third slant tracks extending over at least portions of the first and second slant tracks, the first slant tracks storing an audio signal, the second slant tracks storing an analog video signal, the third slant tracks storing a digital video signal, the digital video signal being free from periodicity of its record waveform and being in a frequency band wider than a frequency band of the analog video signal.
A twenty-ninth aspect of this invention is based on the twenty-eighth aspect thereof, and provides a tape-shaped magnetic recording medium which has a coercive force greater than that of a standard magnetic tape, wherein the analog video signal stored in the second slant tracks is of a predetermined standard format, and a level of the analog video signal recorded by the third and fourth magnetic heads is greater than a predetermined level which is used in a case where an analog video signal is recorded on the standard magnetic tape.
A thirtieth aspect of this invention is based on the twenty-eighth aspect thereof, and provides a tape-shaped magnetic recording medium wherein each of the third slant tracks extends in an area containing a boundary between two neighboring tracks among the second slant tracks.
A thirty-first aspect of this invention is based on the twenty-eighth aspect thereof, and provides a tape-shaped magnetic recording medium wherein longitudinal central lines of the third slant tracks are substantially coincident with longitudinal central lines of the first slant tracks, respectively.
A thirty-second aspect of this invention is based on the twenty-eighth aspect thereof, and provides a tape-shaped magnetic recording medium wherein pictures represented by the digital video signal are equal in contents to pictures represented by the analog video signal.
A thirty-third aspect of this invention provides a method comprising the steps of making a master tape adjoin or contact a slave tape; and applying a bias magnetic field to the master tape to transfer a first magnetization pattern from the master type to the slave tape on a mirror-symmetry basis; wherein the first magnetization pattern is mirror-symmetry with a second magnetization pattern, the second magnetization pattern having an array of first slant tracks, an array of second slant tracks, and an array of third slant tracks, the first slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the second slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the third slant tracks being grouped into pairs each having two neighboring tracks which have different azimuth angles respectively, the azimuth angles of the second slant tracks being different from the azimuth angles of the first slant tracks, the azimuth angles of the third slant tracks being different from the azimuth angles of the second slant tracks, the second slant tracks extending over the first slant tracks, the third slant tracks extending over at least portions of the first and second slant tracks, the first slant tracks storing an audio signal, the second slant tracks storing an analog video signal, the third slant tracks storing a digital video signal, the digital video signal being free from periodicity of its record waveform and being in a frequency band wider than a frequency band of the analog video signal.
A thirty-fourth aspect of this invention is based on the thirty-third aspect thereof, and provides a method wherein the bias magnetic field has a frequency higher than a predetermined frequency which is used in a case where only at least one of an audio signal and an analog video signal is recorded.